Embodiments of the inventive concepts relate to a fuel gauge system, and more particularly, to a fuel gauge system for measuring the amount of current in a battery using a plurality of resistive elements, and to a portable electronic device including the same.
Portable electronic devices using a battery as a power supply typically include a fuel gauge system which measures the amount of current in the battery to estimate the state of charge of the battery. Conventional fuel gauge systems use a method of measuring a voltage of one fixed detection resistive element, and calculating the amount of current based on the measured voltage.
When usual battery current (greater than several hundreds of mA) flows, a voltage applied across both ends of a detection resistive element is greater than an offset voltage of a measurement circuit, so that the amount of current in a battery can be substantially accurately measured using a single fixed detection resistive element. However, when a micro current (less than about 1 mA) flows in a deep sleep mode, a voltage to be measured decreases down to several tens of μV, and a measurement error increases due to the offset voltage of the measurement circuit.